Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

U. Iowa study adds to understanding of salt-taste

03.07.2003


Saltiness often enhances our enjoyment of certain foods -- think French fries or a Margarita. But salt is an essential nutrient for humans and other animals, and far from being a trivial matter of taste, the ability to detect salt is critical for survival. A University of Iowa study provides insight on how humans and other animals are able to detect salt. The study appears in the July 3 issue of Neuron.



"Given that salt is essential for survival, it is not surprising that animals have developed the ability to detect salt, even at low concentrations. This sense allows them to seek out, and then consume salt," said Michael Welsh, M.D., the Roy J. Carver Biomedical Research Chair in Internal Medicine and Physiology and Biophysics, UI Professor, and Howard Hughes Medical Institute Investigator. "We were interested in identifying the receptors that detect small quantities of salt."

The ability to detect when something is too salty is also important. Consuming very high concentrations of salt could be potentially harmful.


Previous research suggested a role for a specific type of protein in salt-sensing. Lei Liu, Ph.D., UI postdoctoral researcher and lead author of the study, and colleagues turned to the fruit fly (Drosophila melanogaster) to investigate these proteins, known as ion channel proteins.

Fruit flies and humans share the ability to detect salt. Fruit flies also respond to salt in ways that are similar to those seen in humans and other animals. For example, fruit flies are attracted to low salt but are repelled by high salt.

"In humans the taste system is pretty much a puzzle because it is hard to study," Liu said. "But in fruit flies it is very easy to study and you can quickly test ideas. Also, fruit flies are a great genetic model where you can easily screen many different genes to determine what they do and how they interact."

The ion channel genes studied are called pickpocket (ppk). The UI team discovered that two of these ion channel genes are involved in the detection of low salt concentrations. The study also suggests that these genes play some role in detecting high salt concentrations, but it is likely that other pathways also are involved in high salt detection.

The UI team focused on the two pickpocket genes, ppk11 and ppk19, because they found that these genes are expressed in body parts of the flies that are involved in taste-sensing. In the fruit fly larva (young flies) the genes are expressed in a body part known as the terminal organ, which resembles a human taste bud.

Using a series of behavioral experiments, the UI researchers discovered that disrupting the two genes impaired the ability of young flies to detect low salt concentrations.

Normally, young fruit flies prefer water containing low salt concentrations to plain water. However, young flies with disrupted genes were unable to detect low salt. Disrupting either gene also altered how both young and adult flies reacted to high salt concentrations.

"When we disrupt the genes we see defects in behavior," Liu said. "To see if the receptor cell itself is being affected, we measured the action potential (nerve impulse) of the receptor cell in the terminal organ of the mutant larva. The response of the receptor cell to salt is reduced by the mutation."

The UI study also showed that the two genes play a role in the ability of flies to distinguish between different types of salt (sodium chloride and potassium chloride). However, disrupting the genes did not seem to affect the fruit flies’ responses to other tastes.

Understanding salt-sensing mechanisms and identifying two ion-channel proteins that detect low salt in fruit flies may be directly relevant to the salt-sensing system in humans.

Although salt is an essential nutrient, individuals with certain conditions such as high blood pressure or heart failure are often advised to reduced their salt intake. Liu said that identifying the receptors involved in salt detection may eventually aid in the design of salt substitutes, which enhance flavor but do not hurt our health.

In addition to Liu and Welsh, Soren Leonard, Ph.D., David Motto, M.D., Ph.D., Margaret Feller, Margaret Price, Ph.D., and Wayne Johnson, Ph.D., UI professor of physiology and biophysics, also were involved in the study. The work was funded in part by grants from the National Institutes of Health.

University of Iowa Health Care describes the partnership between the UI Roy J. and Lucille A. Carver College of Medicine and UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide. Visit UI Health Care online at http://www.uihealthcare.com.



STORY SOURCE: University of Iowa Health Science Relations, 5135 Westlawn, Iowa City, Iowa 52242-1178

Media Contact Jennifer Brown, 319-335-9917, jennifer-l-brown@uiowa.edu

Jennifer Brown | EurekAlert!
Further information:
http://www.uihealthcare.com

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>